# US 11,451,526 B2 · Encrypted 1-bit audio distribution system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,451,526 B2 - Document ID: US11451526B2 - Status: Granted - Kind: B2 - Application number: 16/846,169 - Filed: 2020-04-10 - Published: 2021-10-14 - Granted: 2022-09-20 - Earliest claimed: 2020-04-10 - Assignees: Crestron Electronics, Inc. - Applicants: Crestron Electronics Inc. - Inventors: Philip L. Kirkpatrick - Web page: https://patentgrep.com/patent/US11451526B2 ## CPC - H04L 63/0428: {wherein the data content is protected, e.g. by encrypting or encapsulating the payload} - H04L 63/0485: {Networking architectures for enhanced packet encryption processing, e.g. offloading of IPsec packet processing or efficient security association look-up} - G06F 3/162: {Interface to dedicated audio devices, e.g. audio drivers, interface to CODECs} - G06F 3/165: {Management of the audio stream, e.g. setting of volume, audio stream path} - G10L 19/008: Multichannel audio signal coding or decoding using interchannel correlation to reduce redundancy, e.g. joint-stereo, intensity-coding or matrixing - H04H 60/04: Studio equipment; Interconnection of studios - H04L 12/28: characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks] (wireless communication networks H04W {; arrangements for dividing the transmission path H04W40/00}) - H04R 3/00: Circuits for transducers (arrangements for producing a reverberation or echo sound G10K15/08; amplifiers H03F) - H04R 2201/003: Mems transducers or their use - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) - G10L: SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING - H04H: BROADCAST COMMUNICATION (multiplex communication H04J; pictorial communication aspects of broadcast systems H04N) - H04R: LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS (producing sounds with frequency not determined by supply frequency G10K) ## Abstract An innovative system for transmitting encrypted 1-bit audio over an Ethernet network comprises using an omni-directional micro-electrical-mechanical system acoustic sensor element (11) to provide an analog input signal (33) to a sigma-delta modulator (12) which then creates a pulse density modulated 1-bit data stream (32), at an audio oversampling rate, to a first input of a first exclusive-or (XOR) logic gate (58). The second input of the XOR logic gate is simultaneously presented with a first pseudo-random 1-bit data stream (78), at the same audio oversampling rate, thereby resulting in an encrypted pulse density modulated (PDM) 1-bit data stream (73) at the output of the XOR logic gate. The encrypted PDM 1-bit data stream is clocked into a first-in first-out (FIFO) memory at the audio oversampling rate and is clocked out of the first FIFO memory as Ethernet PDM frame data packages (74) at a predetermined Ethernet PHY transfer rate. ## Claims ### Claim 1 A method for transmitting encrypted audio data over an Ethernet connection, said method comprising the steps of: (a) converting an audio input signal into a first pulse density modulated (PDM) 1-bit data stream at a first predetermined audio oversampling rate; (b) producing an encrypted PDM 1-bit data stream by exclusive-or-ing (XORing) the pulse density modulated 1-bit data stream with a first pseudo-random 1-bit data stream; (c) packaging the encrypted PDM 1-bit data stream into Ethernet PDM frame data by loading a first first-in first-out (FIFO) memory at the first predetermined audio oversampling rate and unloading said first FIFO memory at a first predetermined Ethernet physical layer (PHY) transfer rate; (d) transmitting and receiving said Ethernet PDM frame data from a first Ethernet interface to a second Ethernet Interface; (e) reconstructing the encrypted PDM 1-bit data stream from the Ethernet PDM frame data by loading a second FIFO memory at a second predetermined Ethernet PHY transfer rate and unloading said second FIFO memory at a second predetermined audio oversampling rate; (f) recovering the first PDM 1-bit data stream by XORing the encrypted pulse density modulated 1-bit data stream with a second pseudo-random 1-bit data stream; (g) decimating the first PDM 1-bit data stream into a pulse coded modulated (PCM) N-bit digital data stream at a predetermined audio sampling rate; and (h) converting the N-bit PCM digital data stream into an analog output signal; wherein (i) said first and second pseudo-random 1-bit data streams comprise identical bit sequences at a predetermined encoding rate; and (j) the steps of producing and reconstructing the encrypted PDM 1-bit data stream by XORing are performed at said predetermined encoding rate. ### Claim 2 (depends on 1) The method of claim 1, wherein: (a) the N-bit PCM digital data stream is a 16-bit pulse code modulated digital data stream. ### Claim 3 (depends on 1) The method of claim 1, wherein: (a) said first and second predetermined audio oversampling rates are both a same integer multiple of the predetermined audio sampling rate. ### Claim 4 (depends on 1) The method of claim 1, wherein: (a) said predetermined encoding rate is an integer multiple of the predetermined audio sampling rate. ### Claim 5 (depends on 1) The method of claim 1, wherein: (a) said predetermined audio sampling rate is an integer multiple of the predetermined encoding rate. ### Claim 6 (depends on 1) The method of claim 1, further comprising the steps of: (a) transmitting and receiving a unique seed value from the first Ethernet interface to the second Ethernet Interface; (b) computing said first pseudo-random 1-bit data stream based on this unique seed value; and (c) computing said second pseudo-random 1-bit data stream based on this unique seed value. ### Claim 7 An internet protocol (IP) pulse density modulation (PDM) audio transmitter apparatus adapted to transmit an encrypted PDM 1-bit data stream over an Ethernet network, said apparatus comprising: (a) an acoustic sensor element; (b) a sigma-delta modulator adapted to convert an analog input signal into a pulse density modulated 1-bit data stream at a predetermined audio oversampling rate; (c) a processor and memory adapted to compute and produce a first pseudo-random 1-bit data stream at a predetermined encoding rate; (d) a first exclusive-or (XOR) logic gate operatively connected to the pulse density modulated 1-bit data stream and the pseudo-random 1-bit data stream in such a manner as to produce an encrypted pulse density modulated 1-bit data stream at the predetermined audio oversampling rate; (e) a first first-in first-out (FIFO) memory configured to load the encrypted pulse density modulated 1-bit data stream at said predetermined audio oversampling rate and to unload Ethernet pulse density modulated frame data at a predetermined Ethernet physical layer (PHY) transfer rate; and (f) an Ethernet interface configured to accept the Ethernet frame data at the predetermined Ethernet PHY transfer rate and to transmit Ethernet data packets on a network. ### Claim 8 (depends on 7) The apparatus of claim 7, wherein: (a) said acoustic sensor element is a micro-electrical-mechanical system acoustic sensor element. ### Claim 9 (depends on 7) The apparatus of claim 7, wherein: (a) said predetermined audio oversampling rate is an integer multiple of the predetermined encoding rate. ### Claim 10 (depends on 7) The apparatus of claim 7, wherein the processor and memory are further adapted to: (a) compute a frame checksum (FCS); (b) compute a payload preamble; and (c) load each of said frame checksum and payload preamble into the FIFO memory. ### Claim 11 (depends on 10) The apparatus of claim 10, wherein the payload preamble includes a time stamp. ### Claim 12 (depends on 7) The apparatus of claim 7, wherein the processor and memory are further adapted to: (a) store a predetermined frame checksum (FCS) delay gap; (b) store a predetermined interframe gap; (c) store a predetermined Ethernet frame prefix; (d) store a predetermined internet protocol/user defined protocol (IP/UDP) prefix; and (e) load each of said FCS delay gap, interframe gap, Ethernet frame prefix, and IP/UDP prefix into the FIFO memory. ### Claim 13 An internet protocol (IP) speaker apparatus adapted to receive a 1-channel encrypted pulse density modulation (PDM) 1-bit data stream over an Ethernet network, said apparatus comprising: (a) an Ethernet interface configured to receive Ethernet data packets on a network; (b) a first-in first-out (FIFO) memory configured to load the Ethernet data packets at a predetermined Ethernet physical layer (PHY) transfer rate and to unload an encrypted pulse density modulated 1-bit data stream at a predetermined audio oversampling rate; (c) a processor and memory adapted to compute and produce a pseudo-random 1-bit data stream at a predetermined encoding rate; (d) an exclusive—or (XOR) logic gate operatively connected to the encrypted pulse density modulated 1-bit data stream and the pseudo-random 1-bit data stream in such a manner as to produce an unencrypted pulse density modulated 1-bit data stream at said predetermined audio oversampling rate; (e) a decimator filter adapted to convert the unencrypted pulse density modulated 1-bit data stream into a pulse code modulated N-bit digital data stream at a predetermined audio sampling rate; (f) a digital to analog converter adapted to convert the N-bit pulse code modulated digital data stream into an analog output signal a said predetermined audio sampling rate; and (g) a loudspeaker configured to receive the analog output signal. ### Claim 14 (depends on 13) The apparatus of claim 13, wherein: (a) the N-bit pulse code modulated digital data stream is a 16-bit pulse code modulated digital data stream. ### Claim 15 (depends on 13) The apparatus of claim 13, wherein: (a) said predetermined audio oversampling rate is an integer multiple of the predetermined encoding rate. ### Claim 16 An internet protocol (IP) loudspeaker apparatus adapted to receive a multi-channel encrypted pulse density modulation (PDM) 1-bit data stream over an Ethernet network, said apparatus comprising: (a) a first-in first-out (FIFO) memory configured to load Ethernet data packets at a predetermined Ethernet physical layer (PHY) transfer rate and to unload a plurality of encrypted pulse density modulated 1-bit data streams at a predetermined audio oversampling rate; (c) a processor and memory adapted to compute and produce a plurality of pseudo-random 1-bit data streams at a predetermined encoding rate; (d) a plurality of exclusive-or (XOR) logic gates, each of said XOR gates operatively connected to a corresponding one of said plurality of encrypted pulse density modulated 1-bit data streams and a corresponding one of said plurality of pseudo-random 1-bit data streams in such a manner as to produce a corresponding plurality of unencrypted pulse density modulated 1-bit data streams at said predetermined audio oversampling rate; (e) a plurality of decimator filters adapted to convert each of said plurality of unencrypted pulse density modulated 1-bit data streams into a corresponding plurality of N-bit pulse code modulated (PCM) digital data streams at a predetermined audio sampling rate; (f) a digital audio mixer configured to accept the plurality of N-bit pulse code modulated digital data streams and to produce a combined pulse code modulated N-bit digital data stream multi-channel output; (g) a digital to analog converter adapted to convert the combined PCM N-bit digital data stream into an analog output signal at said predetermined audio sampling rate; and (h) a loudspeaker configured to receive the analog output signal. ### Claim 17 (depends on 16) The apparatus of claim 16, wherein: (a) the combined PCM N-bit data stream is a PCM 16-bit digital data stream.